Edexcel GCSE Chemistry (Higher) — Year 10 Master Notes

Comprehensive vocabulary flashcards covering the Edexcel Year 10 GCSE Chemistry curriculum, including periodic table trends, chemical calculations, acid-base chemistry, metal extraction, and organic fuels.

Atomic number

The number of protons in the nucleus of an atom, which also fixes the position of the element in the periodic table.

Periods

The horizontal rows in the periodic table where the period number tells you the number of occupied electron shells.

Groups

The vertical columns in the periodic table containing elements with similar properties because they have the same number of electrons in their outer shell.

Metals

Elements found on the left and centre of the periodic table that lose electrons to form positive ions (cations) and are shiny, malleable, and good conductors.

Non-metals

Elements found on the top right of the periodic table that gain or share electrons to form negative ions (anions) and are typically dull, brittle, and poor conductors.

Alkali metals

Group 1 elements characterized by having 1 electron in the outer shell, being soft, and reacting vigorously with water to form alkaline solutions.

Halogens

Group 7 elements characterized by having 7 electrons in the outer shell and existing as diatomic molecules like $Cl_2$, $Br_2$, and $I_2$.

Noble gases

Group 0 elements that are chemically inert (unreactive) and monatomic because they already have a full outer shell of electrons.

Monatomic

Existing as single atoms rather than molecules, a characteristic property of the noble gases.

Transition metals

A block of metals in the middle of the periodic table that have high melting points, high densities, form coloured compounds, and act as catalysts.

Relative atomic mass ($A_r$)

The larger number for an element on the periodic table representing its mass relative to other elements.

Relative formula mass ($M_r$)

The sum of the relative atomic mass ($A_r$) values of all the atoms present in a chemical formula.

Mole

The amount of a substance that contains the Avogadro constant of $6.02 \times 10^{23}$ particles.

Avogadro constant

The number of particles in one mole of a substance, equal to $6.02 \times 10^{23}$.

Empirical formula

The simplest whole-number ratio of atoms of each element in a compound.

Molecular formula

The actual number of atoms of each element in one molecule of a compound.

Limiting reactant

The reactant that is completely used up in a chemical reaction and limits the amount of product that can be formed.

Percentage yield

A calculation expressed as: $(\text{actual mass of product obtained} \div \text{theoretical maximum mass of product}) \times 100$.

Atom economy

A measure of the amount of starting materials that end up as useful products, calculated as: $(\text{M}_r \text{ of the desired product} \div \text{sum of the M}_r \text{ of all products}) \times 100$.

Acid

A substance that, in solution, is a source of hydrogen ions, $H^+(aq)$, and has a pH below 7.

Alkali

A base that is soluble in water and is a source of hydroxide ions, $OH^-(aq)$, in solution.

Strong acid

An acid that is completely dissociated (fully ionised) into its ions in aqueous solution, such as $HCl$ or $H_2SO_4$.

Weak acid

An acid that is only partially dissociated in aqueous solution, creating an equilibrium where only a small proportion of molecules release $H^+$ ions.

Base

Any substance, such as a metal oxide or hydroxide, that reacts with an acid to form a salt and water only.

Neutralisation

A reaction between an acid and a base, represented by the ionic equation: $H^+(aq) + OH^-(aq) \rightarrow H_2O(l)$.

Titration

A technique used to find the exact volume of acid and soluble alkali needed to react together to form a pure salt solution.

Concordant results

Titration volumes that are within $0.10\,cm^3$ of each other, used to ensure reliability.

Precipitate

An insoluble solid that emerges from a liquid solution during a chemical reaction between two soluble salts.

Oxidation

The loss of electrons or the gain of oxygen by a substance.

Reduction

The gain of electrons or the loss of oxygen by a substance.

Redox reaction

A reaction in which oxidation and reduction happen at the same time.

Ore

A rock containing enough of a metal compound to make extracting the metal economically viable.

Native

Unreactive metals, such as gold, found in the Earth's crust as uncombined elements.

Electrolysis

The process of using electrical energy to decompose a molten or dissolved ionic compound.

Electrolyte

A molten or dissolved ionic compound that can conduct electricity because its ions are free to move.

Cathode

The negatively charged electrode in an electrolysis cell where reduction occurs.

Anode

The positively charged electrode in an electrolysis cell where oxidation occurs.

Phytoextraction

A biological method of metal extraction where plants absorb metal compounds through roots and are later burned to recover the metal from the ash.

Bioleaching

A biological method using bacteria to produce a leachate solution containing dissolved metal compounds from low-grade ores.

Corrosion

The oxidation of a metal by substances in its environment.

Rusting

Specifically the corrosion of iron and steel, requiring both oxygen and water to form hydrated iron(III) oxide.

Sacrificial protection

A method of preventing rusting by attaching or coating iron with a more reactive metal that corrodes in preference to the iron.

Alloy

A mixture of a metal with other elements, making it harder than the pure metal because different sized atoms distort the layers and prevent them from sliding.

Life Cycle Assessment (LCA)

An evaluation of the environmental impact of a product over its whole life, from raw material extraction to disposal.

Hydrocarbon

A compound that identifies as containing carbon and hydrogen atoms only.

Fractional distillation

The process used to separate crude oil into simpler mixtures called fractions based on their different boiling points.

Viscosity

A measure of how thick a liquid is and how easily it flows; in hydrocarbons, this increases as chain length increases.

Homologous series

A family of compounds with the same general formula, similar chemical properties, and a gradual variation in physical properties.

Alkanes

A homologous series of saturated hydrocarbons with the general formula $C_nH_{2n+2}$.

Saturated

Molecules that contain only single covalent bonds between carbon atoms and hold the maximum possible number of hydrogen atoms.

Incomplete combustion

Burning a fuel with an insufficient supply of oxygen, producing carbon monoxide, soot, and less energy than complete combustion.

Cracking

The process of breaking down larger, saturated alkane molecules into smaller, more useful alkanes and unsaturated alkenes.

Alkenes

A homologous series of unsaturated hydrocarbons that contain at least one carbon-carbon double bond ($C=C$) and have the general formula $C_nH_{2n}$.

Unsaturated

Molecules containing a carbon-carbon double bond, meaning they do not contain the maximum possible number of hydrogen atoms.

Functional group

The specific group of atoms in a molecule responsible for the characteristic chemical reactions of a homologous series, such as the $C=C$ bond in alkenes.

Addition reaction

A reaction where the $C=C$ double bond in an alkene opens up to allow other atoms to bond to the carbon atoms.